from django.shortcuts import render, redirect, get_object_or_404
from .models import Topic, Entry
from .forms import TopicForm, EntryForm
from django.contrib.auth.decorators import login_required
from django.http import Http404


# Create your views here.
def index(request):
    """学习笔记的主页"""
    return render(request, 'learning_logs/index.html')

@login_required
def topics(request):
    """显示所有的主题"""
    topics = Topic.objects.filter(owner=request.user).order_by("date_added")
    context = {'topics': topics}
    return render(request, "learning_logs/topics.html", context)

@login_required
def topic(request, topic_id):
    """显示单个主题及其所有的条目"""
    topic = get_object_or_404(Topic, id=topic_id)
    # 确定主题属于当前用户
    if topic.owner != request.user:
        raise Http404
    entries = topic.entry_set.order_by("-date_added")
    context = {'topic': topic, 'entries': entries}
    return render(request, 'learning_logs/topic.html', context)

@login_required
def new_topic(request):
    """添加新主题"""
    if request.method != "POST":
        # 未提交数据：创建一个新表单
        form = TopicForm()
    else:
        # 是 POST 提交的数据：则对数据进行处理
        form = TopicForm(data=request.POST)
        if form.is_valid():
            new_topic = form.save(commit=False)
            new_topic.owner = request.user
            new_topic.save()
            return redirect("learning_logs:topics")

    # 显示空表单或指出表单数据无效。
    context = {'form': form}
    return render(request, "learning_logs/new_topic.html", context)

@login_required
def new_entry(request, topic_id):
    """添加新条目"""
    topic = Topic.objects.get(id=topic_id)

    if request.method != "POST":
        # 未提交数据：创建一个新表单
        form = EntryForm()
    else:
        # 是 POST 提交的数据：则对数据进行处理
        form = EntryForm(data=request.POST)
        if form.is_valid():
            new_entry = form.save(commit=False)
            new_entry.topic = topic
            new_entry.save()
            return redirect("learning_logs:topic", topic_id=topic_id)

    # 显示空表单或指出表单数据无效。
    context = {'form': form, 'topic': topic}
    return render(request, "learning_logs/new_entry.html", context)

@login_required
def edit_entry(request, entry_id):
    """编辑既有的条目"""
    entry = Entry.objects.get(id=entry_id)
    topic = entry.topic
    if topic.owner != request.user:
        raise Http404

    if request.method != "POST":
        # 初次请求：使用当前条目填充表单
        form = EntryForm(instance=entry)
    else:
        # POST提交的数据：对数据进行处理。
        form = EntryForm(instance=entry, data=request.POST)
        if form.is_valid():
            form.save()                         # 无须再像new_entry那样把topic属性设置了
            return redirect("learning_logs:topic", topic_id=topic.id)

    context = {'entry': entry, 'topic': topic, 'form': form}
    # 如果是初次请求表单，或者是表单填写出错，则使用上下文字典，让render函数使用edit_entry.html渲染页面
    return render(request, "learning_logs/edit_entry.html", context)
